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71.
Saima Chaudhry Muhammad Idrees Mateen Izhar Arshad Kamal Butt Ayyaz Ali Khan 《Current microbiology》2011,62(1):78-83
Polymerase Chain reaction (PCR) assay is considered superior to other methods for detection of Helicobacter pylori (H. pylori) in oral cavity; however, it also has limitations when sample under study is microbial rich dental plaque. The type of gene
targeted and number of primers used for bacterial detection in dental plaque samples can have a significant effect on the
results obtained as there are a number of closely related bacterial species residing in plaque biofilm. Also due to high recombination
rate of H. pylori some of the genes might be down regulated or absent. The present study was conducted to determine the frequency of H. pylori colonization of dental plaque by simultaneously amplifying two genes of the bacterium. One hundred dental plaque specimens
were collected from dyspeptic patients before their upper gastrointestinal endoscopy and presence of H. pylori was determined through PCR assay using primers targeting two different genes of the bacterium. Eighty-nine of the 100 samples
were included in final analysis. With simultaneous amplification of two bacterial genes 51.6% of the dental plaque samples
were positive for H. pylori while this prevalence increased to 73% when only one gene amplification was used for bacterial identification. Detection
of H. pylori in dental plaque samples is more reliable when two genes of the bacterium are simultaneously amplified as compared to one
gene amplification only. 相似文献
72.
A molecular dynamics simulation study of mononuclear iron 15S-lipoxygenase (15S-LOX) from rabbit reticulocytes was performed
to investigate its structure and dynamics; newly developed AMBER force field parameters were employed for the first coordination
sphere of the catalytic iron (II). The results obtained from this study demonstrate that the structural features of the catalytic
iron coordination site are in good agreement with available data obtained from experiments. The motional flexibility of the
N-terminal β-barrel domain is greater than the C-terminal catalytic domain; flexibility was assessed in terms of B-factors and secondary structure calculations. The significant features obtained for the relative motional flexibility of
these two domains of 15S-LOX in solution as well as the isolated C-terminal domain were analyzed in terms of radius of gyration
and maximum diameter, which correlated well with the structural flexibility of 15-lipoxygenase-1 in solution as probed by
small-angle X-ray scattering. The motional flexibility indicates interdomain motion between the N-terminal β-barrel and the
C-terminal catalytic domain; this was further verified by the evaluation of central bending in the solvated LOX molecule,
which identified an unstructured stretch of amino acids as the interdomain linker. The average bending angle confirmed significant
central bending between these two domains, which was linked to the high degree of motional freedom of the N-terminal β-barrel
domain in aqueous solutions. This can be considered to have biological relevance for membrane binding as well as for regulating
the catalytic domain. 相似文献
73.
Fahmida Parveen Zaheer Ahmed Nizamani Fang Gan Xingxiang Chen Xiuli Shi Shahnawaz Kumbhar Alam Zeb Kehe Huang 《Biological trace element research》2014,157(3):266-274
AFB1 is a mycotoxin which exerts their cytotoxicity through increasing oxidative damage in target organ. Kidney is one of target organs vulnerable to damage caused by AFB1. In this study, Madin-Darby canine kidney (MDCK) cells were used to evaluate the AFB1-induced cell damage by the MTT assay. The results revealed that the toxic effect of AFB1 on MDCK cells is both dose and time dependent. Half maximal toxic concentration (IC50) was noted at 0.25 μg/ml of AFB1. Further, protective effect of six different concentrations (0.2, 0.8, 1, 2, 4, and 8 μM) of selenomethionine (SeMet) was observed against 0.25 μg/ml of AFB1-induced damage. The results showed that 0.25 μg/ml of AFB1 caused significant increase in oxidative stress, which was demonstrated by significant increase of malondialdehyde (MDA) level, reduction of intracellular GSH level, as well as GPX1 activity and mRNA level in MDCK cells when compared with control. SeMet protected the cells from AFB1-induced oxidative damage in a dose-dependant manner. Good protection could be achieved between 1 and 4 μM of concentration. Amid this range, MDA level significantly decreased while intracellular GSH level and GPX1 activity in addition to mRNA level significantly increased. Moreover, cell viability was significantly improved. It could be concluded that SeMet is a potential antioxidative agent to alleviate AFB1-induced oxidative stress. 相似文献
74.
This study describes a simple approach for enhanced secretory expression of bubaline somatotropin (BbST) in the methylotropic yeast Pichia pastoris. A Muts Pichia transformant carrying multi-copy, non-codon optimized BbST cDNA sequence, expressed and secreted the recombinant protein into the culture medium to a level of 25 % of the total proteins in the culture supernatant, after 120 h of induction. Inclusion of polysorbate-80 in the inducing medium resulted in a significant improvement in the BbST expression (up to 45 % of the total culture supernatant proteins) with concomitant reduction in the induction time to 48 h. The amount of BbST obtained was 148 mg/L, which was around fivefold higher than that obtained without the surfactant. BbST was purified to near homogeneity by FPLC on Q-sepharose FF anion-exchange column. Protein authenticity was judged by SDS-PAGE and western blot analyses. A bioassay based on proliferation of Nb2 rat lymphoma cell lines confirmed that the purified, recombinant BbST is biologically active. Use of polysorbate-80 in combination with methanol, during the induction phase, is likely to have general applicability in lowering the induction time and enhancing the secretory expression of other commercially important proteins in Muts strains of P. pastoris. 相似文献
75.
Abdul Wadood Muhammad Riaz Amir ul Mulk Momin Khan Sobia Ahsan Haleem Sulaiman Shams Sahib Gul Ayaz Ahmed Muhammad Qasim Farman Ali Zaheer Ul-Haq 《Bioinformation》2014,10(5):299-307
Urease is an important enzyme both in agriculture and medicine research. Strategies based on urease inhibition is critically
considered as the first line treatment of infections caused by urease producing bacteria. Since, urease possess agro-chemical and
medicinal importance, thus, it is necessary to search for the novel compounds capable of inhibiting this enzyme. Several
computational methods were employed to design novel and potent urease inhibitors in this work. First docking simulations of
known compounds consists of a set of arylidine barbiturates (termed as reference) were performed on the Bacillus pasteurii (BP)
urease. Subsequently, two fold strategies were used to design new compounds against urease. Stage 1 comprised of the energy
minimization of enzyme-ligand complexes of reference compounds and the accurate prediction of the molecular mechanics
generalized born (MMGB) interaction energies. In the second stage, new urease inhibitors were then designed by the substitution
of different groups consecutively in the aryl ring of the thiobarbiturates and N, N-diethyl thiobarbiturates of the reference ligands..
The enzyme-ligand complexes with lowest interaction energies or energies close to the calculated interaction energies of the
reference molecules, were selected for the consequent chemical manipulation. This was followed by the substitution of different
groups on the 2 and 5 positions of the aryl ring. As a result, several new and potent diethyl thiobarbiturates were predicted as
urease inhibitors. This approach reflects a logical progression for early stage drug discovery that can be exploited to successfully
identify potential drug candidates. 相似文献
76.
Shokit Hussain Akrema Rahisuddin Zaheer Khan 《Bioprocess and biosystems engineering》2014,37(5):953-964
The work reported in this paper describes the preparation, morphology, stability and sensitivity of Ag-nanoparticles towards sunlight using Allium sativum, garlic extract for the first time. The synthesized silver particles show an intense surface plasmon resonance band in the visible region at 410 nm. The position of the wavelength maxima, blue and red shift, strongly depends on the sunlight and pH. TEM analysis revealed the presence of spherical, different size (from 5.0 to 30 nm) and garlic constituents bio-conjugated, stabilized and/or layered silver nanoparticles. The concentrations of garlic extract, cetyltrimethylammonium bromide, Ag+ ions and reaction time play vital roles for nucleus formation and the growth processes. Sulfur-containing biomolecules of extract, especially cysteine, are responsible for the reduction of Ag+ ions into metallic Ag0. The agglomeration number of the silver nanoparticles (N Ag) and the average number of free electrons per particle (n fe) are calculated and discussed. 相似文献
77.
Iqbal Ahmad Kiran Qadeer Saima Zahid Muhammad Ali Sheraz Tehmina Ismail Waqar Hussain Izhar Ahmad Ansari 《AAPS PharmSciTech》2014,15(5):1324-1333
The degradation kinetics of 5 × 10−5 M cyanocobalamin (B12) and hydroxocobalamin (B12b) in the presence of ascorbic acid (AH2) was studied in the pH range of 1.0–8.0. B12 is degraded to B12b which undergoes oxidation to corrin ring cleavage products. B12b alone is directly oxidized to the ring cleavage products. B12 and B12b in degraded solutions were simultaneously assayed by a two-component spectrometric method at 525 and 550 nm without interference from AH2. Both degrade by first-order kinetics and the values of the rate constants at pH 1.0–8.0 range from 0.08 to 1.05 × 10−5 s−1 and 0.22–7.62 × 10−5 s−1, respectively, in the presence of 0.25 × 10−3 M AH2. The t1/2 values of B12 and B12b range from 13.7 to 137.5 h and 2.5–87.5 h, respectively. The second-order rate constants for the interaction of AH2 with B12 and B12b are 0.05–0.28 × 10−2 and 1.10–30.08 × 10−2 M−1 s−1, respectively, indicating a greater effect of AH2 on B12b compared to that of B12. The kobs–pH profiles for both B12 and B12b show the highest rates of degradation around pH 5. The degradation of B12 and B12b by AH2 is affected by the catalytic effect of phosphate ions on the oxidation of AH2 in the pH range 6.0–8.0.KEY WORDS: ascorbic acid, cyanocobalamin, degradation, hydroxocobalamin, kinetics, two-component spectrometry 相似文献
78.
Y. Saima A. K. Das K. K. Sarkar A. K. SenSr P. Sur 《International journal of biological macromolecules》2000,27(5)
An acidic heteropolysaccharide has been isolated from the tropical angiosperm Feronia limonia syn. F. elephantum (family: Rutaceae). A partially carboxymethylated α-(1–4) polygalacturonan backbone structure with 2- and 2,4-O-α-
-rhamnopyranosyl, 2- and 2,3-O-α-
-arabinofuranosyl and 3-, 2,4-and terminal α-
-galactopyranosyl bearing side chains has been tentatively assigned. The preliminary study in the murine model showed some significant in vivo Ehrlich ascites carcinoma cell growth inhibition. 相似文献
79.
80.